* Astronomy

Title: IC 5181: An S0 Galaxy with Ionised Gas on Polar Orbits
Author: Alessandro Pizzella, Lorenzo Morelli, Enrico Maria Corsini, Elena Dalla Bonta`, Mary Cesetti

The nearby S0 galaxy IC 5181 is studied to address the origin of the ionised gas component that orbits the galaxy on polar orbit. We perform detailed photometric and spectroscopic observations measuring the surface brightness distribution of the stars (I-band), ionised gas of IC 5181 (H-alpha narrow band), the ionised-gas and stellar kinematics along both the major and minor axis, and the corresponding line strengths of the Lick indices. We conclude that the galaxy hosts a geometrically and kinematically decoupled component of ionized gas. It is elongated along the galaxy minor axis and in orthogonal rotation with respect to the galaxy disk. The result is suggesting that the gas component is not related to the stars having an external origin. The gas was accreted by IC 5181 on polar orbits from the surrounding environment.

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